FXUS62 KGSP 260703
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
303 AM EDT FRI MAY 26 2006

.SHORT TERM /TODAY THROUGH SUNDAY/...
SCATTERED DEEP CONVECTION CONTINUES TO DEVELOP OVER THE NC MNTNS IN 
ADVANCE OF EXPANSIVE MCS MOVING ACROSS NORTHEAST TN/SOUTHEAST KY. 
THE SCT CONVECTION APPEARS TO BE TIED WITH WEAK UPGLIDE REGIME AND
BL CONVERGENCE AT THE NOSE OF A 30-40 KT LLJ. LATEST SPC 
MESOANALYSIS ALSO INDICATES A SUBSTANTIAL AMOUNT OF ELEVATED
INSTABILITY ACROSS OUR MNTNS ATTM. WITH THESE FACTORS IN MIND...AND 
CONSIDERING THE MCS APPROACHING THE NORTHERN MNTNS...WILL FEATURE 
HEALTHY POPS ACROSS THE MNTNS THIS MORNING...GENERALLY IN THE 50-60 
RANGE. INSTABILITY WEAKENS RAPIDLY EAST OF THE BLUE RIDGE...SO 
EXPECT GRADUAL WEAKENING OF THE MCS AS IT CONTINUES TO MOVE EAST. IN 
FACT...LATEST RADAR IMAGERY INDICATES THE COLD POOL HAS ALREADY 
BEGUN TO ACCELERATE AWAY FROM THE LEADING CONVECTIVE LINE...A SURE 
SIGN THAT THE COLD POOL HAS BECOME TOO DEEP FOR DEEP LAYER SHEAR TO 
SUSTAIN INITIATION OF NEW CELLS...PROBABLY SIGNALING THE BEGINNING 
OF THE END FOR THIS MCS. (INDEED THERE HAS BEEN AN OBVIOUS DECREASE 
IN THE STRENGTH OF THE INDIVIDUAL CELLS OVER THE PAST HALF HOUR OR 
SO.) THEREFORE...WILL DROP POPS OFF SUBSTANTIALLY EAST OF THE MNTNS 
THIS MORNING. 

THE QUESTION THEN BECOMES WHAT HAPPENS THIS AFTERNOON AS 
DESTABILIZATION COMMENCES. AVAILABLE GUIDANCE IS IN GOOD AGREEMENT 
THAT THE AIRMASS SHOULD BECOME MODERATELY UNSTABLE. A LEE TROUGH AND 
OUTFLOW BOUNDARY LEFT BEHIND BY THIS MORNING/S CONVECTION WILL 
PROVIDE LOW LEVEL FOCI FOR ADDITIONAL DEVELOPMENT...WHILE A MID- 
LEVEL SW TROUGH WILL ROTATE ACROSS THE AREA DURING THE AFTERNOON. 
DEEP LAYER SHEAR WILL BE ADEQUATE FOR ORGANIZED CONVECTION...AND 
WITH LINEAR FORCING PROVIDED BY THE SW TROUGH...WOULDN/T BE AT ALL 
SURPRISED TO SEE A SECONDARY STRONG-TO-SEVERE SQUALL LINE DEVELOP 
ACROSS THE AREA THIS AFTERNOON. AM TEMPTED TO INCREASE POPS TO 
LIKELY ACROSS MUCH OF THE CWFA FOR LATER TODAY...BUT WILL ALLOW THE 
DAY SHIFT TO EVALUATE WHAT AFFECTS (IF ANY) THIS MORNING/S 
CONVECTION WILL HAVE ON CHANCES FOR ADDITIONAL AFTERNOON DEVELOPMENT 
BEFORE TAKING THAT LEAP. WITH GOOD INSTABILITY EXPECTED ALONG WITH 
SUBSTANTIAL MID-LEVEL DRY AIR...EXPECT AT LEAST A FEW DAMAGING WIND 
GUSTS AND LARGE HAIL EVENTS THIS AFTERNOON...SO WILL ISSUE A SEVERE 
WEATHER OUTLOOK TO HIGHLIGHT THE THREAT.   

WEAK COLD FRONT MOVES THROUGH THE AREA THIS EVENING...AND ALTHOUGH 
THERE WILL BE VIRTUALLY NO COOLING BEHIND THIS FEATURE...IT WILL 
INTRODUCE DRIER AIR TO THE REGION...SO THE REMAINDER OF THE SHORT 
TERM WILL BE VERY WARM AND DRY...WITH THE EXCEPTION PERHAPS OF 
ISOLATED MOUNTAIN CONVECTION DURING THE AFTERNOON AND EVENING.    
&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
THE MEDIUM RANGE PERIOD LOOKS RATHER PERSISTENT WITH A BROAD AND 
WEAK UPPER LOW SPINNING SOMEWHERE OFF THE SOUTHEAST COAST AND A HIGH 
AMPLITUDE RIDGE OVER THE MS/OH VALLEY AND GREAT LAKES...WITH THE 
WESTERN CAROLINAS STUCK SOMEWHERE IN BETWEEN. FOR MONDAY AT LEAST... 
THE UPPER RIDGE SHOULD BE LOCATED FAR ENOUGH EAST TO KEEP US DRY. 
HOWEVER...THESE FEATURES RETROGRADE SOMEWHAT DURING THE EARLY PART 
OF THE WEEK. THE MODELS SHOW MOISTURE ON THE WEST SIDE OF THE 
MOUNTAINS AND CLOSER TO THE UPPER LOW CIRCULATION ON TUESDAY AND 
WEDNESDAY...WITH RELATIVELY DRIER AIR OVER THE PIEDMONT. THIS FAVORS 
DIURNAL CONVECTION FORCED BY DIFFERENTIAL HEATING OVER THE 
MOUNTAINS...BUT A DRY FORECAST FROM THE FOOTHILLS AND EAST. SOME 
ATLANTIC MOISTURE MOVES FARTHER WEST ON THURSDAY WHICH SHOULD ALLOW 
FOR THE POSSIBILITY OF CONVECTION EVERYWHERE. HAVE FOLLOWED A BLEND 
OF HPC AND MEX GUIDANCE FOR TEMPS THROUGHOUT.
&&

.AVIATION...
MCS OVER TN SLOWLY APPROACHING FROM THE NW WILL BRING INCREASED 
CHANCE CONVECTION TO AREA TODAY. EXPECT MVFR FOG KAVL AND KAND... 
TEMPO IFR FOG KAND 10-12Z. SCT SHOWERS AND TSTMS WILL DEVELOP AHEAD 
OF SYSTEM IN UNSTABLE AIR. HAVE BROUGHT VCSH TO KAVL 08Z...CB BY 
12Z...VCTS BY 17Z. WITH AFTN HEATING...UPPER WAVE AND SFC 
BOUNDARY... EXPECT CB CLOUDS NEAR ALL TAF SITES BY 18Z. WINDS WILL 
INCREASE FROM THE SW TODAY...15G25KT THRU THE AFTN...NW WINDS KAVL 
DUE TO VALLEY ORIENTATION.
&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&

$$

SHORT TERM...LANE
LONG TERM...MOORE
AVIATION...RB